Bring a pot of water to boiling. Add the pierogies and cook for 5-7 minutes or until they are cooked through. Drain, reserving 1/2 cup of the pasta water.

Meanwhile, put the sausage in a skillet over medium high heat and cook for 6-8 minutes or until browned.

Reduce heat to medium and add in the peppers, onions, and garlic. Cook for 5 or 6 minutes or until the vegetables begin to soften.

Add in the oregano, butter, salt and pepper and cook for 1-2 minutes.

Add the pierogies along with 1/4 cup of the reserved pasta water and cook for 1-2 minutes or until everything is well combined.

Serve hot.